Bottom line: A single loose stool in an otherwise bright cat can be watched, but diarrhoea with blood, repeated vomiting, lethargy, a painful belly, or a kitten needs a vet promptly. The biggest risk with diarrhoea in cats is dehydration, and in cats that stop eating alongside it, a serious liver condition can follow.
| Situation | Suggested action |
|---|---|
| One loose stool, cat otherwise bright | Monitor 24–48 hours |
| Diarrhoea + vomiting, or lasting >48 hours | Vet visit |
| Blood in diarrhoea, or black tarry stools | Same-day vet visit |
| Kitten with diarrhoea, lethargy, or vomiting | Emergency vet now |
Why cats get diarrhoea
Diarrhoea is a sign, not a disease, it means the gut is irritated, inflamed, or not absorbing water properly. In cats it's common, and the cause ranges from a simple dietary upset to serious systemic disease. The concern is that cats tolerate dehydration poorly and can develop complications (like fatty liver if they stop eating) faster than dogs, so a "wait and see" approach is riskier than it is in a dog.
What can cause it
Dietary causes are common: a sudden food change, a dietary indiscretion, food intolerance, or a rich treat that upset the gut. Infectious causes include parasites (worms, giardia, and Tritrichomonas, a stubborn parasite in young cats), and bacteria. Inflammatory bowel disease is very common in middle-aged and older cats and often shows as chronic or intermittent soft stools and weight loss.
More serious causes include a swallowed foreign body, pancreatitis (often with a painful belly and not eating), liver or kidney disease, hyperthyroidism in older cats, poisoning, and certain cancers. Stress can cause a transient upset. Some medications, including antibiotics, disturb the gut flora.
When to worry, the red flags
A bright, drinking cat with one loose stool can be watched for a day or two. See a vet for:
- Blood in the diarrhoea (red streaks, or black, tarry, foul stools)
- Repeated vomiting alongside the diarrhoea, dehydration risk is high
- Not eating, fatty liver risk rises quickly in cats
- Lethargy, weakness, or hiding, the cat is systemically unwell
- A painful or tender belly, or straining with no result
- A kitten, dehydration and low blood sugar develop fast
- Diarrhoea lasting more than 48 hours, even if the cat seems okay
- Known access to a toxin, or a possible swallowed object (string, hair ties)
- Weight loss, increased thirst, or chronic intermittent diarrhoea, points to ongoing disease
What to do right now
- Offer small amounts of water frequently to prevent dehydration; if vomiting too, offer ice cubes to lick.
- Don't withhold food for long, unlike dogs, fasting cats risks fatty liver. Offer a bland, easily digested diet in small meals.
- Try a bland diet, plain boiled chicken, or a prescription intestinal diet, in small frequent meals, then transition back slowly.
- Keep a record, frequency, consistency, colour, and any blood, to tell the vet.
- Call your vet if any red flag appears, if it's a kitten, or if it hasn't improved within 48 hours.
What NOT to do
- ❌ Don't starve a cat, fasting can trigger fatty liver.
- ❌ Don't give human anti-diarrhoea drugs without vet advice; some are unsafe and some causes shouldn't be masked.
- ❌ Don't feed rich or fatty "recovery" foods.
- ❌ Don't delay with a kitten, with blood, or with vomiting alongside, dehydration can become dangerous within hours.
How a vet diagnoses and treats it
Your vet will examine your cat, assess hydration, and may run a faecal test for parasites or infection, bloodwork if systemic illness is suspected, and sometimes imaging if a blockage is possible. Treatment depends on the cause, fluids, intestinal protectants, probiotics, a prescription diet, anti-parasitics or antibiotics, and rarely surgery for a blockage. Most routine cases resolve well with supportive care, and chronic cases often respond to a diet trial and IBD management.
Preventing the next bout
Change foods gradually, keep bins and rich foods out of reach, keep worming up to date, and for cats with recurrent upsets, ask your vet about food intolerance or IBD. In multi-cat households, keep litter trays clean to limit the spread of parasites.
When to wait, and when to act now
A bright adult cat with one loose stool and no other signs can be managed at home for 24–48 hours. Blood, vomiting, not eating, lethargy, a painful belly, or a kitten means a vet, and a collapsed or vomiting kitten is an emergency right now.
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Frequently Asked Questions
Disclaimer: This article is for educational purposes only and is not a substitute for professional veterinary advice. If you're concerned about your pet's health, use our AI triage assessment or consult a licensed veterinarian.
